(19)
(11) EP 0 484 948 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
09.06.1993 Bulletin 1993/23

(43) Date of publication A2:
13.05.1992 Bulletin 1992/20

(21) Application number: 91119011.4

(22) Date of filing: 07.11.1991
(51) International Patent Classification (IPC)5: E21B 36/04, E21B 17/00, E21B 43/24
(84) Designated Contracting States:
DE GB NL

(30) Priority: 07.11.1990 US 610080

(71) Applicant: UENTECH CORPORATION
Tulsa, Oklahoma 74145 (US)

(72) Inventors:
  • Bridges, Jack E.
    Park Ridge, Ill.60068 (US)
  • Bajzek, Thomas J.
    Wood Dale, Ill.60191 (US)
  • Hofer, Kenneth E.
    Chicago Ridge, Ill.60415 (US)
  • Spencer, Homer L.
    Calgary, Alberta 22PT2P4C8 (CA)
  • Smith, Larry G.
    Calgary, Alberta T2A3V7 (CA)
  • Young, Vincent R.
    Calgary, Alberta T3E5Y6 (CA)

(74) Representative: Heusler, Wolfgang, Dipl.-Ing. et al
Dr. Dieter von Bezold Dipl.-Ing. Peter Schütz Dipl.-Ing. Wolfgang Heusler Brienner Strasse 52
D-80333 München
D-80333 München (DE)


(56) References cited: : 
   
       


    (54) Robust electrical heating systems for mineral wells


    (57) Electrical heating systems for mineral wells, particularly oil wells, in which the reservoir or "pay zone" is heat stimulated or some well components (e.g., the tubing) are heated, or both, by electrical power supplied to a multi-perforate electrode have the operating efficiency enhanced by effectively terminating the heating electrode, at both its top and bottom, at a distance inwardly of the pay zone equal to at least three times the diameter of the well casing. In some systems the electrical power connection to the main heating electrode is made through a section of the production tubing of the well, with an electrical contactor interconnecting the tubing and the electrode in the level of the pay zone; these systems also provide electrical isolation, within critical height limits, for the production tubing and the pump rod. Delivery of electrical power downhole of the well may be accomplished through an electrical cable, which may or may not be appropriately armored. Specific electrode constructions combine conductive and insulating materials to counteract galvanic corrosion while maintaining mechanical strength.






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